The impact of corrosion on the oil, gas and geothermal industry is big and affects both capital and operational expenditures (CAPEX and OPEX). There is a growing public awareness and rising concerns with well integrity and health, safety and the environment (HSE).
One of the first steps for corrosion mitigation is to evaluate downhole tubular. The reduction of metal thickness leads to a loss of mechanical strength and structural failure. When metal pitting accelerates in localized zones, very considerable structural weakening may result from a relatively small amount of metal loss. Additionally, the alteration or loss of surface properties including erosion, increased fluid flow friction at the pipe surface, surface reflectivity or heat transfer across a surface, cause such weakness.
Corrosion evaluation using electric-line logging is of growing importance in the industry. Technologies that can evaluate multiple barriers are vital for cost-effective evaluations as rig time is saved by not having to retrieve the completion to evaluate production casings. This is the case especially in the offshore environment where the casing design is generally more complicated and consists of extra number of casing strings. Current technologies available include magnetic flux leakage or eddy current, or to some extent ultrasonic which has some limited capability of multi-barrier evaluation.
A multi-sensor electromagnetic corrosion tool (EM) has been developed especially for multi-barrier evaluations; the technology is based on pulsed eddy current physics. When combined with conventional multi-finger calipers and other tools such as radial cement bond logs or noise detection technologies, it offers a better understanding of well integrity.